The dispute over the politically charged designation erupted during a House hearing, reflecting continued bickering over the definition and scope of the threat posed to the United States by gangland-style violence that has claimed more than 35,000 lives over the past six years.

Threat to U.S.

Republican lawmakers, led by Rep. Michael McCaul, R-Austin, contend unrelenting bloodshed threatens to create a "failed state controlled by criminals" that could "become a safe haven for terrorists who we know are attempting to enter the United States through our porous border."

McCaul introduced legislation Wednesday to add six Mexican drug cartels to the worldwide list of 47 designated "foreign terrorist organizations" to bolster the U.S. campaign against destabilizing criminal organizations in neighboring Mexico.

"In my judgment, Mexico is losing this war - and so are we," McCaul told the hearing Thursday by his investigations subcommittee of the House Homeland Security Committee. "The president needs to recognize this issue. We face a serious issue in our backyard, and we need to deal with it."

But administration officials and Democrats such as Rep. Sheila Jackson Lee, D-Houston, called existing laws adequate to deal with drug kingpins and trans-national smuggling operations as well as the threat of so-called "spill-over violence" across the U.S.-Mexico border.

Are current laws enough?

Current laws, Jackson Lee said, "give sufficient help for law enforcement to go after the Mexican drug trafficking organizations."

Rep. William Keating, D-Mass., ranking Democrat on McCaul's subcommittee, played down the scope of the threat to the United States in line with Democrats' assessment.

"It is my understanding that most of the violence could be construed as a turf battle between rival drug traffickers," the lawmaker told the hearing, noting that 84 percent of Mexico's drug-related homicides occurred last year in four of the nation's 32 states.

Brian Nichols, an executive in the State Department's bureau of international narcotics and law enforcement affairs, warned that designating cartels terrorist organizations on a par with al-Qaida would complicate collaborative U.S. efforts with Mexico to stem the north-bound flow of narcotics and the south-bound flow of drug proceeds and U.S. weapons.